Ventilator Settings Research Articles

Effect of automated versus conventional ventilation on mechanical power of ventilation-A randomized crossover clinical trial.

Mechanical power of ventilation, a summary parameter reflecting the energy transferred from the ventilator to the respiratory system, has associations with outcomes. INTELLiVENT-Adaptive Support Ventilation is an automated ventilation mode that changes ventilator settings according to algorithms that target a low work-and force of breathing. The study aims to compare mechanical power between automated ventilation by means of INTELLiVENT-Adaptive Support Ventilation and conventional ventilation in critically ill patients. International, multicenter, randomized crossover clinical trial in patients that were expected to need invasive ventilation > 24 hours. Patients were randomly assigned to start with a 3-hour period of automated ventilation or conventional ventilation after which the alternate ventilation mode was selected. The primary outcome was mechanical power in passive and active patients; secondary outcomes included key ventilator settings and ventilatory parameters that affect mechanical power. A total of 96 patients were randomized. Median mechanical power was not different between automated and conventional ventilation (15.8 [11.5-21.0] versus 16.1 [10.9-22.6] J/min; mean difference -0.44 (95%-CI -1.17 to 0.29) J/min; P = 0.24). Subgroup analyses showed that mechanical power was lower with automated ventilation in passive patients, 16.9 [12.5-22.1] versus 19.0 [14.1-25.0] J/min; mean difference -1.76 (95%-CI -2.47 to -10.34J/min; P < 0.01), and not in active patients (14.6 [11.0-20.3] vs 14.1 [10.1-21.3] J/min; mean difference 0.81 (95%-CI -2.13 to 0.49) J/min; P = 0.23). In this cohort of unselected critically ill invasively ventilated patients, automated ventilation by means of INTELLiVENT-Adaptive Support Ventilation did not reduce mechanical power. A reduction in mechanical power was only seen in passive patients. Clinicaltrials.gov (study identifier NCT04827927), April 1, 2021. https://clinicaltrials.gov/study/NCT04827927?term=intellipower&rank=1.

New noninvasive modalities in long-term pediatric ventilation: a scoping review.

Long-term noninvasive ventilation modalities for the pediatric population have undergone a continuous evolution. Hybrid noninvasive ventilation modalities have been recently introduced in clinical practice. Combining the advantages of conventional ventilation, hybrid modes use algorithms that automatically adjust the ventilator's settings to achieve a predefined ventilation target. Most of the recommendations on the use and settings of hybrid noninvasive ventilation modalities in children are derived from adult experience. Therefore, there is a lack of evidence on its implementation in pediatric chronic respiratory diseases. This scoping review aims to map the existing information regarding the use of hybrid ventilation modalities in the pediatric population and identify knowledge or research gaps. We performed a literature search using MEDLINE and Pubmed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. We included 13 studies (ten studies on average volume-assured pressure-support ventilation; two studies on intelligent volume-assured pressure-support ventilation; and one study on adaptive servoventilation). The use of new noninvasive ventilation modes in the pediatric population has been applied for the treatment of neuromuscular and hypoventilation syndromes as an alternative therapeutic option in the case of the failure of conventional noninvasive ventilation. Their widespread use has been hampered by the limited evidence available. Longitudinal studies on a larger number of patients are needed to confirm their effectiveness and evaluate their long-term clinical and functional outcomes.

Recruitment-Potential-Oriented Mechanical Ventilation Protocol and Narrative Review for Patients with Acute Respiratory Distress Syndrome.

Even though much progress has been made to improve clinical outcomes, acute respiratory distress syndrome (ARDS) remains a significant cause of acute respiratory failure. Protective mechanical ventilation is the backbone of supportive care for these patients; however, there are still many unresolved issues in its setting. The primary goal of mechanical ventilation is to improve oxygenation and ventilation. The use of positive pressure, especially positive end-expiratory pressure (PEEP), is mandatory in this approach. However, PEEP is a double-edged sword. How to safely set positive end-inspiratory pressure has long been elusive to clinicians. We hereby propose a pressure-volume curve measurement-based method to assess whether injured lungs are recruitable in order to set an appropriate PEEP. For the most severe form of ARDS, extracorporeal membrane oxygenation (ECMO) is considered as the salvage therapy. However, the high level of medical resources required and associated complications make its use in patients with severe ARDS controversial. Our proposed protocol also attempts to propose how to improve patient outcomes by balancing the possible overuse of resources with minimizing patient harm due to dangerous ventilator settings. A recruitment-potential-oriented evaluation-based protocol can effectively stabilize hypoxemic conditions quickly and screen out truly serious patients.

Influence of Early Total Enteral Feeding in Preterm Infants with Respiratory Distress Syndrome

Plain Language SummaryThe objective of this secondary analysis of data from the randomized trial comparing less invasive surfactant therapy (LISA) with InSurE method of surfactant administration among preterm infants with respiratory distress syndrome (RDS) is to demonstrate the feasibility of ETEF in hemodynamically stable preterm neonates on respiratory support.In this randomized control trial comparing LISA versus InSurE among preterm infants with RDS between 26 and 34 weeks of gestation, 150 infants were enrolled with 117 being hemodynamically stable. In 33 patients, early total enteral feeding could not be started due to various reasons – 7 babies had absence/reversal of end-diastolic flow (A/REDF) on antenatal Doppler, 15 babies had shock and required inotropic support on day 1 of life, 8 babies had higher ventilatory settings at the time of admission, and in the 3 babies, the abdomen was not soft to start total enteral feeding. Full-volume enteral feeding without any parenteral supplementation was started on day 1 of life using the mother’s own milk (MoM) or donor human milk (≤32 weeks of GA) and MoM or preterm formula (33–34 weeks of GA). The data were analyzed to assess the proportion of babies developing feed intolerance and/or NEC and factors associated with failure of ETEF. Out of these 117 babies, 102 tolerated ETEF, and 15 had one or more episodes of FI requiring parenteral supplementation, but none developed NEC. There was a statistically significantly increased incidence of culture-positive sepsis as well as the requirement of antibiotic therapy for possible sepsis in babies with failure of ETEF. There was no difference in the morbidities noted such as intraventricular hemorrhage grade 2 or more, patent ductus arteriosus requiring medical or surgical management, retinopathy of prematurity requiring treatment, and NEC stage II or more. Our study suggests that hemodynamically stable preterm infants with RDS on respiratory support can be successfully fed with exclusive enteral feeds started immediately post-birth. ETEF results in early attainment of full feeding and reduces the incidence of sepsis and the duration of hospital stay without increasing the risk of NEC.

The Ventilatory Changes of Pediatric Peroral Endoscopic Myotomy Patients.

Peroral endoscopic myotomy (POEM) has proven to be a successful treatment method for achalasia in both adult and pediatric patients. Yet, there is a lack of evidence for anaesthetic management of pediatric patients who underwent POEM procedure. In this study, we aim to present perioperative and postoperative management strategies for pediatric patients with achalasia from in anaesthesia aspect. Medical records were reviewed for 16 pediatric patients at a single center who underwent POEM procedure for achalasia between 2017 and 2020. Patients' data regarding demographics, preoperative diet, body mass index, perioperative monitoring and vitals, airway management, anaesthesia maintenance, mechanical ventilation settings duration of recovery, length of stay, pain management and adverse events were evaluated. The study cohort included 7 female and 9 male patients with a mean age of 5.5 years. Anaesthesia maintenance was provided with 0.8-1.2 minimum alveolar concentration sevoflurane in a 40-60% O2-air mixture, Remifentanil infusion and bolus doses of Rocuronium. The median age was 3 years for patients ventilated in pressure controlled ventilation mode and 10 years in volume controlled ventilation mode. Respiration rate and minute ventilation were adjusted to maintain end tidal carbon dioxide (ETCO2) below 45 mmHg. Needle decompression was applied for 14 patients (87.5%) for treatment of capnoperitoneum. The mean procedure duration and recovery room duration were 66 (±22.9) minutes and 62 (±21) minutes, respectively. Postoperative pain management is provided with paracetamol and tramadol in total 8 patients (50%). There was no adverse event during postoperative period and all patients discharged in a mean time of 3 days. POEM has demonstrated encouraging outcomes in terms of safety and effectiveness in pediatric patients. Due to challenging nature of the pediatric patients, it is important to acknowledge that the procedure requires specialized anaesthesia management. Management of perioperative complications of increased ETCO2 requires understanding the physiologic results of pneumo-mediastinum and pneumo-peritoneum. Beside the known anaesthetic management strategies, a tailored approach should be adopted for each patient. Further investigations should be conducted to develop standardized management.

Toward occupant-centric system: Multicriteria optimization of hybrid displacement–personalized ventilation system using computational fluid dynamics with computer-simulated person

Engineers have integrated general ventilation systems with personalized ventilation (PV) to achieve energy efficiency while providing good indoor air quality (IAQ) and thermal comfort. Previous studies conducted parametric analyses of PV by varying its flow rate and temperature, analyzing energy, IAQ, and thermal comfort while keeping main ventilation settings constant, even though the latter significantly affect the general flow field. Therefore, computational fluid dynamics simulation is performed to simultaneously optimize the above-mentioned three outputs in an office with displacement ventilation (DV) and PV by varying the DV supply flow rate and temperature, the fraction of outlet air being resupplied to inlet or DV recirculation, and PV supply flow rate and temperature. We utilize the Taguchi design to minimize the number of simulations as well as use the “technique for order preference by similarity to ideal solution” (TOPSIS) coupled with Taguchi's signal-to-noise ratio analysis for optimization. Four optimization cases are investigated by varying the thermal comfort and IAQ parameters from volume-averaged to occupant-centric values, such as the skin temperature and inhaled concentration. Results show that occupant-centric optimization presents low energy requirements with acceptable IAQ and thermal comfort compared with volume-averaged optimization, which can be attributed to imperfect mixing conditions. Furthermore, the DV settings and thermal plumes significantly affect the direction of jet released by the PV, which does not improve the IAQ. This underscores the importance of considering the aforementioned effects in maximizing the PV potential. Nevertheless, the PV system functions as intended under a flow rate of 6 L/s.

Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust – Effect of temperature and ventilation

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18–16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6–40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

Correlation analysis of central venous pressure and Intra-thoracic pressures in Acute Respiratory Distress Syndrome mechanical ventilated patients, a pilot Study

Abstract Background Positive end expiratory pressure can affect measurement of central venous pressure through increased intrathoracic pressure. However, when positive end expiratory pressure (PEEP) is applied, central venous pressure and pleural pressure often increases more than right atrial pressure, so that transmural right atrial pressure (true filling pressure) decreases. Aim of the study Primary end point was to recognizing correlation coefficient between mean CVP and intra- thoracic pressures on volume-controlled mode and spontaneous modes on same population of mechanically ventilated ARDS patients. The secondary end point is to compare the correlation coefficient R during both modes with parameters of ventilatory settings. Patient and Methods A cohort observational prospective study was done enrolling single group of patients with acute respiratory distress syndrome, who necessitate mechanical ventilation more than two days after connection to ventilators, the study was performed with demonstration of central venous pressure in cmH2O upon application of needed PEEP. Central venous catheter inserted for measuring CVP were processed in accordance with the standard guidelines. Results There were statistically significant differences between control and support group regarding the PEEP, Plateau pressure, mean CVP and mean airway pressure MAP. The data were higher in control than support group with p-value &amp;lt;0.001, 0.002 and 0.004, respectively. There was statistically significant positive correlation between R and CVP in the control group with p &amp;lt; 0.001 and r = 0.918. There was statistically significant positive correlation between R and ΔPIT in support group with p 0.001 and r = 0.926. The correlation between CVP and R among the control group was R = 0.028 + 0.032 * CVP with p-value &amp;lt;0.001, whereas the correlation between ΔPIT and R among the support group was R = 0.465 + 0.020 * ΔPIT with p-value = 0.022 Conclusion The relation between hemodynamics change of central venous pressures and intrathoracic pressure is new independent marker for evaluating ARDS mechanically ventilated patients. Values of R correlation are different in controlled mode relative to spontaneous mode during ARDS ventilated patients.

Efficacy of home healthcare on the management of tracheostomy patients.

To evaluated the home healthcare efficacy in managing tracheostomy patients at King Abdulaziz Medical City under the Ministry of National Guard Health Affairs. Home healthcare is care provided to patients in the convenience of their homes to ensure high-quality care based on healthcare providers' supervision. This retrospective cohort study utilizing a non-probability consecutive sampling technique, including all available tracheal patients with no exclusion criteria, was carried out in Riyadh, Saudi Arabia, between January 2019 and June 2022. The collected data included patient demographic variables and respiratory settings (ventilation type, daily ventilation need, tracheostomy duration, and ventilator settings). The outcomes included mortality rate and therapeutic outcomes of tracheal management. Of the 183 patients in the study, the most common type of respiratory-related infection was pneumonia (53%). Unlike respiratory-related causes, The mortality rate of patients admitted to the intensive care unit that was unrelated to respiratory causes was statistically significant (57%) (p=0.003). The mortality rate of patients who used aerosol tracheal collars (34%) was markedly higher than mechanically ventilated patients (57%) (p=0.004). The mortality rate following discharge from HHC was 40%, and was higher among patients aged >70 years (47%) (p=0.04). Pneumonia was associated with the majority of ventilator-related infections and resulted in hospital readmissions. Ensuring proper practices and caregiver education is crucial to decrease the incidence of ventilator-related infections.

Pulmonary Artery Pressures and Mortality During Venoarterial ECMO: An ELSO Registry Analysis.

Systemic hemodynamics and specific ventilator settings have been shown to predict survival during venoarterial extracorporeal membrane oxygenation (ECMO). How the right heart (the right ventricle and pulmonary artery) affect survival during venoarterial ECMO is unknown. We aimed to identify the relationship between right heart function with mortality and the duration of ECMO support. Cardiac ECMO runs in adults from the Extracorporeal Life Support Organization Registry between 2010 and 2022 were queried. Right heart function was quantified via pulmonary artery pulse pressure (PAPP) for pre-ECMO and on-ECMO periods. A multivariable model was adjusted for modified Society for Cardiovascular Angiography and Interventions stage, age, sex, and concurrent clinical data (ie, pulmonary vasodilators and systemic pulse pressure). The primary outcome was in-hospital mortality. A total of 4442 ECMO runs met inclusion criteria and had documentation of hemodynamic and illness severity variables. The mortality rate was 55%; nonsurvivors were more likely to be older, have a worse Society for Cardiovascular Angiography and Interventions stage, and have longer pre-ECMO endotracheal intubation times (P<0.05 for all) than survivors. Increasing PAPP from pre-ECMO to on-ECMO time (ΔPAPP) was associated with reduced mortality per 2 mm Hg increase (odds ratio, 0.98 [95% CI, 0.97-0.99]; P=0.002). Higher on-ECMO PAPP was associated with mortality reduction across quartiles with the greatest reduction in the third PAPP quartile (odds ratio, 0.75 [95% CI, 0.63-0.90]; P=0.002) and longer time on ECMO per 10 mm Hg (beta, 15 [95% CI, 7.7-21]; P<0.001). Early on-ECMO right heart function and interval improvement from pre-ECMO values were associated with mortality reduction during cardiac ECMO. Incorporation of right heart metrics into risk prediction models should be considered.

Characterising indoor air quality in private vehicle cabins under unprecedented traffic conditions during COVID-19 lockdown

Air pollution negatively impacts human health, yet it is rarely studied inside vehicles. This study aimed to characterise indoor air quality (IAQ) in vehicle cabins, focusing on the concentrations of key pollutants and the influence of various factors on IAQ including vehicle-specific characteristics (self-pollution), traffic intensity, ventilation type, and enclosed spaces like parking garages. It addressed a significant literature gap by using real-world driving data, a multipollutant approach, real-time monitoring, and a detailed log of influencing factors. Additionally, part of the study was conducted during the COVID-19 lockdown, providing an unprecedented opportunity to gather real-world data with reduced traffic emissions. Forty trips were conducted with four diesel vehicles of different ages and emission standards. Concentrations of VOCs, CO, CO₂, NO₂, SO₂, O₃, and PM₁, PM₂.₅, PM₁₀, and TSP were monitored, alongside detailed logbook entries. This study evidenced the formation of O₃ inside vehicle cabins under conditions of high NO₂ and/or VOC concentrations and direct sunlight, a phenomenon not previously reported. Results also showed that IAQ inside vehicle cabins depended largely on vehicle-specific factors, the surrounding environment, and indoor-outdoor air exchange. CO, NO₂, SO₂, and PM levels varied mainly with the external environment and air exchange, while CO₂ levels were influenced primarily by ventilation settings. The concentrations of certain pollutants exceeded reference levels for indoor environments, potentially posing health risks to occupants. Further research is needed to study the pioneer evidence of O3 formation and to develop a comprehensive health risk assessment, thereby contributing to developing specific IAQ guidelines for vehicles.

Severe respiratory acidosis contributing to refractory hyperkalemia: a case series of COVID-19 patients with renal failure

Introduction: Respiratory acidosis (RA) is not known to cause severe hyperkalemia. However, an exception to this general rule was observed in three patients with severe COVID-19 complicated with renal failure in our center. Objectives: The current study investigated the explanation for hyperkalemia refractory to renal replacement therapy in patients with severe COVID-19 with hypercarbia and renal failure in a tertiary care center. Patients and Methods: In this study, we present a case series of three patients with severe COVID-19 with hypercarbia and dialysis-requiring renal failure who developed persistent hyperkalemia refractory to renal replacement therapy. We studied various causes of persistent hyperkalemia, such as acid‒base disorder, a high turnover state, exogenous administration, rhabdomyolysis, and hypoaldosteronism. Results: All three patients initially presented with episodes of severe hyperkalemia, which were ameliorated after RA was corrected. All of these patients had worsening pulmonary function, after which the hyperkalemia could not be corrected, corresponding to persistent RA. The evidence that there was a contribution of RA to hyperkalemia was further strengthened by the observations of patient 1, in whom the hyperkalemia was only corrected after changing ventilator settings and who was unresponsive to dialysis. We studied the dialysate effluent in patient 3, and the results showed satisfactory removal of potassium with no improvement in the high serum potassium levels. Another interesting finding was that although the dialysate sodium concentration was greater than the serum sodium concentration, there was a decrease in the serum sodium concentration, indicating a reduced movement of sodium into the extracellular space. Conclusion: In our study, metabolic acidosis alone could not explain the high serum potassium levels. Moreover, hyperkalemia was corrected after RA was corrected, indicating that the latter might have been the predominant cause of hyperkalemia in these scenarios. The presence of renal failure and low serum bicarbonate levels might have been the factors contributing to decreased Na+-K+-ATPase activity in the setting of RA, which contributed to severe hyperkalemia in all three patients.

Improving breathing effort estimation in mechanical ventilation via optimal experiment design

Estimation of the breathing effort and relevant lung parameters of a ventilated patient is essential to keep track of a patient’s clinical condition. The aim of this paper is to increase estimation accuracy through experiment design. The main method is an experiment design approach across multiple breaths within a linear regression framework to accurately identify the patient’s condition. Identifiability and persistence of excitation are used to formulate an estimation problem with a unique solution. Furthermore, Fisher information is used for assessing the parameters sensitivity to slight changes of the ventilator settings to improve the variance of the estimation. The estimation method is applied to simulated patients who breathe regularly but also to patients who have variable breathing patterns. A virtual experiment is conducted for both situations to generate estimation results. The results are analyzed using mathematical tools and show that uniquely estimating the lung parameters and breathing effort over multiple breaths for both regularly and variably breathing patients is possible in the presented framework. The proposed estimation method obtains clinically relevant estimates for a large set of breathing disturbances from the simulation case-study.

Mechanical power during robotic-assisted laparoscopic prostatectomy: an observational study

BackgroundRobotic-assisted laparoscopic radical prostatectomy (RALP) requires pneumoperitoneum and steep Trendelenburg position. Our aim was to investigate the influence of the combination of pneumoperitoneum and Trendelenburg position on mechanical power and its components during RALP.MethodsSixty-one prospectively enrolled patients scheduled for RALP were studied in supine position before surgery, during pneumoperitoneum and Trendelenburg position and in supine position after surgery at constant ventilatory setting. In a subgroup of 17 patients the response to increasing positive end-expiratory pressure (PEEP) from 5 to 10 cmH2O was studied.ResultsThe application of pneumoperitoneum and Trendelenburg position increased the total mechanical power (13.8 [11.6 – 15.5] vs 9.2 [7.5 – 11.7] J/min, p < 0.001) and its elastic and resistive components compared to supine position before surgery. In supine position after surgery the total mechanical power and its elastic component decreased but remained higher compared to supine position before surgery. Increasing PEEP from 5 to 10 cmH2O within each timepoint significantly increased the total mechanical power (supine position before surgery: 9.8 [8.4 – 10.4] vs 12.1 [11.4 – 14.2] J/min, p < 0.001; pneumoperitoneum and Trendelenburg position: 13.8 [12.2 – 14.3] vs 15.5 [15.0 – 16.7] J/min, p < 0.001; supine position after surgery: 10.2 [9.4 – 10.7] vs 12.7 [12.0 – 13.6] J/min, p < 0.001), without affecting respiratory system elastance.ConclusionMechanical power in healthy patients undergoing RALP significantly increased both during the pneumoperitoneum and Trendelenburg position and in supine position after surgery. PEEP always increased mechanical power without ameliorating the respiratory system elastance.

Mean airway pressure - Minute ventilation product (mM): A simple and universal surrogate equation to calculate mechanical power in both volume and pressure controlled ventilation

Introduction Mechanical power represents the energy delivered by a mechanical ventilator onto the lungs. It incorporates all the variables participating in ventilator-induced lung injury, including driving pressure, tidal volume, positive end expiratory pressure, and respiratory rate. The pitfall of mechanical power is its mathematical complexity, as the gold standard method of calculation involves deriving the inspiratory area under the pressure-volume curve of each breath. Prior studies attempted to create simplified equations, they lack clinical utility as calculations cannot be done by solely looking at ventilator settings or they require manipulation of variables. There are also different formulas depending on the type of the mode of ventilation used. This study offers a simplified, universal equation called the mean airway pressure - Minute ventilation product (mM equation) which renders mechanical power clinical application more feasible at the bedside. Methods and Statistics Data collection used the online SIVA simulator, which simulate mechanical ventilation and calculate the geometrical area of the inspiratory limb of the pressure-volume curve. Different combinations of passive scenarios with varying compliances (10-80 ml/cmH2O) and resistances (5-30 cmH2O/L/S) in each the VCV and PCV modes were accomplished by adjusting ventilator settings with respiratory rate (5-40 BPM), tidal volume (150-700 mL), DP (5-30 cmH2O), and PEEP (0-15 cmH2O), with different inspiratory times in PCV and different flows rates in the VCV. A total of 2,000 values were collected in each mode. Range of Mechanical power measured by the simulator: 0.1 - 105 J/min and range of mM equation (mean airway pressure x Minute ventilation): 0.37 - 820 cmH2O/L/min. Pearson correlation coefficients were calculated to compare the relationship of the mM equation to the measured MP, and linear regressions were used for predicting the MP derived from the mM equation in each mode separately and when combining all data from both modes. T-test for equal variance and Bland Altmann plot were used to compare the reference MP measured (MPR) from the simulator to the one derived from the Mm formula (MPD). Results There was a statistically significant linear relationship (P &lt; 0.001) and strong correlation of determination (R2 = 0.931), CI (0.961, 0.967) between the mM formula and the gold-standard method of calculating mechanical power for the combined two modes. For the VCV: there was a statistically significant linear relationship (P &lt; 0.001) and strong correlation of determination (R2 = 0.936), CI (-0.963, 0.971). For the PCV: there was a statistically significant linear relationship (P &lt; 0.001) and strong correlation of determination (R2 = 0.936), CI (-0.964, 0.970). A linear regression model predicted the MP from the mM as follows: for both modes MP = 0.13 (mM) + 3.41, for PCV MP = 0.15 (mM) + 3.79, for VCV MP = 0.13 (mM) + 2.48. The derived mechanical power from the mM was not statistically different (P 0.498) from the calculated reference MP using two sample T-tests assuming equal variance. The Bland-Altman plot for VCV mode showed a mean of 0.78 with 95% CI (0.34, 1.22), SD (-13.27, 14.83). In PCV, a mean of - 0.53 with 95% CI (-0.68, -0.38), SD (-6.28, 5.22). For both modes, a mean of 0, with 95% CI (-0.2, 0.2), SD (-10.06, 10.05). Conclusion The mM equation and its MP derived formula is a reliable method of calculating mechanical power. The simplicity and universal nature of its calculation can provide significant clinical utility at the bedside. More studies are needed to validate this method of calculation. Keywords: Mechanical power, mean airway pressure, minute ventilation

Current State of Ventilator Setting and Their Relationship with Mortality Rate in Patients under Mechanical Ventilation: A Cross-Sectional Study

Background: Given the importance of implementing lung protective strategies to prevent lung injury caused by ventilators and death of patients, it is necessary to monitor the current condition of hospitals and examine the relationship between the parameters set on the ventilators and patient mortality. This study conducted to determine the current state of ventilator setting and their relationship with mortality rate in patients under mechanical ventilation: a cross-sectional study. Methods: This is a cross-sectional study that was conducted between June to December 2020 in one of the hospitals affiliated to Tehran University of Medical Sciences. The initial tidal volume set on the ventilator was recorded for 304 patients under mechanical ventilation and then, their heights were measured and their tidal volumes were determined based on the standard formula. Other parameters set on the ventilator as well as systolic and diastolic blood pressures of patients were also recorded and their survival rate was investigated. The data was analyzed by SPSS software, using descriptive statistics and logistic regression model. Results: Among patients, who were under mechanical ventilation, 77.6% were hospitalized in intensive care units and the rest were hospitalized in general wards. The mean adjusted tidal volume for patients was 472.91 ± 32.13 ml. The mean peak inspiratory pressure and plateau pressure were 28.00±6.98 and 13.88±4.93 CmH2O, respectively. Also, 37.2% of patients died during the hospitalization. The results of adjusted odds ratio based on multivariate logistic regression model for predictors of mortality rate showed that the variables of patients' age [OR=1.040 (1.019-1.062)], the hospital’s general ward in comparison with the ICU [OR=11.379 (5.130-25.240)] and the peak inspiratory pressure [OR=1.072 (1.007-1.141)] had a direct and significant relationship with mortality rate (in all cases P&lt;0.05). Meanwhile, the plateau pressure [OR=0.886 (0.808 -0.972)] had an inverse and significant relationship with mortality rate (P&lt;0.05). Conclusion: Despite the recommendations regarding lung protective strategies, in some cases, some parameters set in the ventilator are outside the recommended levels, which can effect on patients mortality. So monitoring and controlling the implementation of lung protective strategies and paying attention to controlling pressures set on the ventilator are among measures that should be taken in medical centers in order to prevent lung injuries and maintain patient safety.

Identifying low-dimensional trajectories of mechanically-ventilated patient systems: Empirical phenotypes of joint patient+care processes to enhance temporal analysis in ARDS research.

Refined management of mechanically ventilation is an obvious target for improving patient outcomes, but is impeded by the nature of data for study and hypothesis generation. The connections between clinical outcomes and temporal development of iatrogenic injuries current lung-protective ventilator settings remain poorly understood. Analysis of lung-ventilator system (LVS) evolution at relevant timescales is frustrated by data volume and multiple sources of heterogeneity. This work motivates, presents, and validates a computational pipeline for resolving LVS systems into the joint evolution of data-conditioned model parameters and ventilator information. Applied to individuals, the workflow yields a concise low-dimensional representation of LVS behavior expressed in phenotypic breath waveforms suitable for analysis. The effectiveness of this approach is demonstrated through application to multi-day observational series of 35 patients. Individual patient analyses reveal multiple types of patient-oriented dynamics and breath behavior to expose the complexity of LVS evolution; less than 10% of phenotype changes related to ventilator settings changes. Dynamics are shown to including both stable and unstable phenotype transitions as well as both discrete and continuous changes unrelated to ventilator settings. At a cohort scale, 721 phenotypes constructed from individual data are condensed into a set of 16 groups that empirically organize around certain settings (positive end-expository pressure and ventilator mode) and structurally similar pressure-volume loop characterizations. Individual and cohort scale phenotypes, which may be refined by hypothesis-specific constructions, provide a common framework for ongoing temporal analysis and investigation of LVS dynamics.

The new neural pressure support (NPS) mode and the helmet: did we find the dynamic duo?

BackgroundNoninvasive ventilation (NIV) is commonly used in clinical practice to reduce intubation times and enhance patient comfort. However, patient-ventilator interaction (PVI) during NIV, particularly with helmet interfaces, can be challenging due to factors such as dead space and compliance. Neurally adjusted ventilatory assist (NAVA) has shown promise in improving PVI during helmet NIV, but limitations remain. A new mode, neural pressure support (NPS), aims to address these limitations by providing synchronized and steep pressurization. This study aims to assess whether NPS per se improves PVI during helmet NIV compared to standard pressure support ventilation (PSV).MethodsThe study included adult patients requiring NIV with a helmet. Patients were randomized into two arms: one starting with NPS and the other with PSV; the initial ventilatory parameters were always set as established by the clinician on duty. Physiological parameters and arterial blood gas analysis were collected during ventilation trials. Expert adjustments to initial ventilator settings were recorded to investigate the impact of the expertise of the clinician as confounding variable. Primary aim was the synchrony time (Timesync), i.e., the time during which both the ventilator and the patient (based on the neural signal) are on the inspiratory phase. As secondary aim neural-ventilatory time index (NVTI) was also calculated as Timesync divided to the total neural inspiratory time, i.e., the ratio of the neural inspiratory time occupied by Timesync.ResultsTwenty-four patients were enrolled, with no study interruptions due to safety concerns. NPS demonstrated significantly longer Timesync (0.64 ± 0.03 s vs. 0.37 ± 0.03 s, p < 0.001) and shorter inspiratory delay (0.15 ± 0.01 s vs. 0.35 ± 0.01 s, p < 0.001) compared to PSV. NPS also showed better NVTI (78 ± 2% vs. 45 ± 2%, p < 0.001). Ventilator parameters were not significantly different between NPS and PSV, except for minor adjustments by the expert clinician.ConclusionsNPS improves PVI during helmet NIV, as evidenced by longer Timesync and better coupling compared to PSV. Expert adjustments to ventilator settings had minimal impact on PVI. These findings support the use of NPS in enhancing patient-ventilator synchronization and warrant further investigation into its clinical outcomes and applicability across different patient populations and interfaces.Trial registrationThis study was registered on www.clinicaltrials.gov NCT06004206 Registry URL: https://clinicaltrials.gov/study/NCT06004206 on September 08, 2023.

Stress–strain curve and elastic behavior of the fibrotic lung with usual interstitial pneumonia pattern during protective mechanical ventilation

Patients with acute exacerbation of lung fibrosis with usual interstitial pneumonia (EUIP) pattern are at increased risk for ventilator-induced lung injury (VILI) and mortality when exposed to mechanical ventilation (MV). Yet, lack of a mechanical model describing UIP-lung deformation during MV represents a research gap. Aim of this study was to develop a constitutive mathematical model for UIP-lung deformation during lung protective MV based on the stress–strain behavior and the specific elastance of patients with EUIP as compared to that of acute respiratory distress syndrome (ARDS) and healthy lung. Partitioned lung and chest wall mechanics were assessed for patients with EUIP and primary ARDS (1:1 matched based on body mass index and PaO2/FiO2 ratio) during a PEEP trial performed within 24 h from intubation. Patient’s stress–strain curve and the lung specific elastance were computed and compared with those of healthy lungs, derived from literature. Respiratory mechanics were used to fit a novel mathematical model of the lung describing mechanical-inflation-induced lung parenchyma deformation, differentiating the contributions of elastin and collagen, the main components of lung extracellular matrix. Five patients with EUIP and 5 matched with primary ARDS were included and analyzed. Global strain was not different at low PEEP between the groups. Overall specific elastance was significantly higher in EUIP as compared to ARDS (28.9 [22.8–33.2] cmH2O versus 11.4 [10.3–14.6] cmH2O, respectively). Compared to ARDS and healthy lung, the stress/strain curve of EUIP showed a steeper increase, crossing the VILI threshold stress risk for strain values greater than 0.55. The contribution of elastin was prevalent at lower strains, while the contribution of collagen was prevalent at large strains. The stress/strain curve for collagen showed an upward shift passing from ARDS and healthy lungs to EUIP lungs. During MV, patients with EUIP showed different respiratory mechanics, stress–strain curve and specific elastance as compared to ARDS patients and healthy subjects and may experience VILI even when protective MV is applied. According to our mathematical model of lung deformation during mechanical inflation, the elastic response of UIP-lung is peculiar and different from ARDS. Our data suggest that patients with EUIP experience VILI with ventilatory setting that are lung-protective for patients with ARDS.

The impact of hypovolemia and PEEP on recirculation in venovenous ECMO: an experimental porcine model

BackgroundRecirculation is a common problem in venovenous extracorporeal membrane oxygenation (VV ECMO) and may limit the effect of ECMO treatment due to less efficient blood oxygenation or unfavorable ECMO and ventilator settings. The impact of hypovolemia and positive end expiratory pressure (PEEP) on recirculation is unclear and poorly described in guidelines, despite clinical importance. The aim of this study was to investigate how hypovolemia, autotransfusion and PEEP affect recirculation in comparison to ECMO cannula distance and circuit flow.MethodsIn anesthetized and mechanically ventilated pigs (n = 6) on VV ECMO, we measured recirculation fraction (RF), changes in recirculation fraction (∆RF), hemodynamics and ECMO circuit pressures during alterations in PEEP (5 cmH2O vs 15 cmH2O), ECMO flow (3.5 L/min vs 5.0 L/min), cannula distance (10–14 cm vs 20–26 cm intravascular distance), hypovolemia (1000 mL blood loss) and autotransfusion (1000 mL blood transfusion).ResultsRecirculation increased during hypovolemia (median ∆RF 43%), high PEEP (∆RF 28% and 12% with long and short cannula distance, respectively), high ECMO flow (∆RF 49% and 28% with long and short cannula distance, respectively) and with short cannula distance (∆RF 16%). Recirculation decreased after autotransfusion (∆RF − 45%).ConclusionsIn the present animal study, hypovolemia, PEEP and autotransfusion were important determinants of recirculation. The alterations were comparable to other well-known factors, such as ECMO circuit flow and intravascular cannula distance. Interestingly, hypovolemia increased recirculation without significant change in ECMO drainage pressure, whereas high PEEP increased recirculation with less negative ECMO drainage pressure. Autotransfusion decreased recirculation. The findings are interesting for clinical studies.